MAIN OUTCOME MEASUREMENTS:Perceived improvement in symptoms at least 6 months after treatment, perceived change in visual analog scale score, assessment of functional pain, and overall satisfaction.
On average, patients were 48 years old, had symptoms for a median of 18 months before treatment, and answered the survey on average 15 months after treatment. Overall, 82% of patients indicated moderate to complete improvement in symptoms. The most common injection sites were the lateral epicondyle, Achilles, and patellar tendons. Other sites treated included the rotator cuff, hamstring, gluteus medius, and medial epicondyle, among others. Furthermore, 60% of patients received only 1 injection, 30% received 2 injections, and 10% received 3 or more injections. Patients' perceived decrease in visual analog scale score was 75%, from ± to ± (-, SD , 95% confidence interval - to -, P < .0001). In addition, at follow-up, 95% of patients reported having no pain at rest that disrupted their activities of daily living and 68% reported no pain during activities. A total of 85% of patients were satisfied with the procedure.
In this retrospective study, in which we evaluated administration of PRP for chronic tendinopathy, we found that the majority of patients reported a moderate (>50%) improvement in pain symptoms.
In medicine , a joint injection ( intra-articular injection ) is a procedure used in the treatment of inflammatory joint conditions , such as rheumatoid arthritis , psoriatic arthritis , gout , tendinitis , bursitis , Carpal Tunnel Syndrome ,  and occasionally osteoarthritis .   A hypodermic needle is injected into the affected joint where it delivers a dose of any one of many anti-inflammatory agents, the most common of which are corticosteroids . Hyaluronic acid , because of its high viscosity , is sometimes used to replace bursa fluids.  The technique may be used to also withdraw excess fluid from the joint.